The semiconductor industry has experienced rapid growth due to continuous improvements in the integration density of a variety of electronic components (e.g., transistors, diodes, resistors, capacitors, etc.). For the most part, this improvement in integration density has come from repeated reductions in minimum feature size, which allows more components to be integrated into a given area. As the demand for even smaller electronic devices has grown recently, there has grown a need for smaller and more creative packaging techniques of semiconductor dies.
As semiconductor technologies evolve, wafer-level chip scale package (WLCSP) structures have emerged as an effective alternative to further reduce the physical size of semiconductor devices. In a WLCSP structure, active devices such as transistors and the like are formed at the top surface of a substrate of the WLSCP structure.
A current WLCSP process includes a four mask structure including two polyimide layers, a redistribution layer (RDL), and an under bump metallization (UBM) structure. There is a high cost for such a structure. In addition, there is no solder bump protection for the wafer-level chip scale package's large die structure.